Soundness Proof Assistant

SkillDev tools

Assist in constructing type soundness proofs using progress and preservation theorems

Instructions available. Your AI can read the instructions. Execution depends on the setup they require.

Account requirements not reviewed. Check the skill instructions before use; ahel provides instructions and does not run this skill.

Add ahel to your AI once: Claude, ChatGPT, Cursor, Claude Code or Codex. Then ask it to use this.

Then ask your AI: use the Soundness Proof Assistant skill

What this skill tells your AI

The instructions your AI receives, as published by a5c-ai/babysitter in library/specializations/domains/science/computer-science/skills/soundness-proof-assistant/SKILL.md and read by ahel’s review.

Purpose

Provides expert guidance on constructing type soundness proofs for programming language type systems.

Capabilities

Progress theorem proof templates
Preservation theorem proof templates
Substitution lemma generation
Canonical forms lemma derivation
Proof case enumeration
Mechanization guidance

Usage Guidelines

Lemma Identification: Identify required supporting lemmas
Progress Proof: Prove progress theorem by cases
Preservation Proof: Prove preservation theorem
Substitution Lemmas: Prove substitution preserves typing
Mechanization: Translate to proof assistant

Tools/Libraries

Coq
Agda
Lean
Twelf

Signals

GitHub stars: 2k
Forks: 112
Last commit: Sep 2026

Advanced

Item type: skill
Key: soundness-proof-assistant
Source: github.com/a5c-ai/babysitter

github.com/a5c-ai/babysitter